We have become a society of lazy wildlife wannabe shooters. Let me give everyone a key axiom of telephoto shooting. With equally good lenses, lets say primes, using a 300mm lens closer to the subject will get you sharper results than shooting an equally good 400mm lens from father away. It is simply the physics of optical resolution, period. The only time you shoot at a longer focal length is when you can't get closer or its too dangerous. Not when you are too lazy to get out of the car and get closer to the subject. We all succumb to this on occasion, whether we are good or not. There is nothing that you can shoot with a 300mm lens that can't be shot better with a 200mm lens if you just move your feet.

Kent Gittings

Agreed, but it's not always about being 'lazy', sometimes there's absolutely no opportunity to even get closer. Think birding - can't climb a tree or walk closer without your subject taking off most of the time. Wildlife shooting - same idea. Sports shooting - sidelines are pretty much a hard limit, unless you want to get booted from the game

This is also where more MP can help - cropping doesn't have as much of an IQ drawback.

Except , of course , that we sometimes choose to shoot with a longer focal length for creative purposes : not merely to fill the frame with some distant object which we could indeed just move closer to , but because a longer focal length , with its different field of view , can give a different perspective , often compressing distance between subjects and objects much further away in the background ; conversely , we often use short focal lengths when we want to emphasise space and size , and to bring subjects very much into the foreground .--With kind regards